Q: Our plum tree usually produces lots of fruit. Some years, it is so heavily laden, we prop up the limbs to keep them from breaking. This year the tree produced only a few plums. Is it dying?
A: You have not provided many details, so it is difficult to say if your plum tree is dying. Fruit trees fail to bear for many reasons. Let’s walk through the most common causes and see if any fit your plum tree’s circumstances.
Fruit trees must be well-established to bear a good crop. In general, plum trees do not bear fruit reliably for four to six years after planting. Given that your tree produced good harvests in the past, the tree must be old enough to bear fruit.
Some plum trees require cross-pollination by a different variety of plums to produce fruit; some don’t. Since your tree produced good harvests in the past, it must have had what it needed as far as a cross-pollinator. If the cross-pollinating tree died or was removed, however, this could be the problem.
You report a heavy load of fruit in past years. An especially heavy crop one year can inhibit bud initiation and poor fruit production the following year.
If this happens repeatedly, the tree gets into a cycle of producing a good crop every other year. To prevent every-other-year fruit production, limit the number of plums your tree must support. Thin the fruit when it is the size of a large marble (i.e., in early summer). Leave one plum every 2-4 inches along the branch.
Plum trees are relatively cold hardy, but late cold spells can damage buds and blossoms leading to poor fruit production. Some parts of Clallam County experienced freezing temperatures in May, when many fruit trees were in bloom. Was this the case in your orchard?
In the future, if your tree is budding out and a heavy frost is expected, cover it with floating row cover or old bed sheets. Hang incandescent or Christmas tree lights under the cover to offer additional protection.
Even if the flowers were not damaged by frost, cold temperatures during bloom can lead to inadequate pollination. Bees, the primary pollinators of most fruit trees, generally don’t like cool temperatures (or rain or wind). Without bees to pollinate, fruit will not set.
To encourage bees to visit your plum tree, plant a variety of flowers in your garden and avoid using pesticides, especially when plants are in bloom. If cool temperatures commonly occur where you live during bloom, consider introducing mason bees into your orchard. Mason bees will fly in cooler temperatures and even light rain.
If your plum tree set fruit, but the fruit fell off the tree before it matured, tree health might be an issue. Weak or diseased trees produce fruit of poor quality or no fruit at all.
Look for diseases, insects and other pests that could affect tree health. Make sure you are providing your tree what it needs as far as sun exposure, water and nutrients.
Q: I am new to the area. I planted kale starts in late March. The plants survived a late cold snap in May, but they bolted in June. What did I do wrong?
A: Kale is a biennial plant which means its life cycle is completed over a two-year period. During the first year after germination, kale grows vegetatively, producing leaves. As days shorten and temperatures cool in late fall, it stops growing and goes dormant.
As temperatures warm in late winter, it starts growing again. Soon thereafter it usually develops flowers, goes to seed and dies.
Kale will bolt (i.e., produce seeds) during the first season after planting for two reasons: 1) stress and 2) temperature fluctuations.
Stress can result from improper planting, inadequate care, or diseases and pests. Kale likes full sun and good draining, slightly acidic soil (pH 5.5-6.8). Keep plants well-watered; mulch around plants to keep their roots cool. Look for and treat any pests or diseases.
Warm temperatures after planting followed by cooler temperatures and warm temperatures in the first season can trick kale into thinking that it has gone through the winter and is time to produce seeds.
Bolting is more common among plants started from seed indoors or purchased starts, especially if transplanting into the garden is delayed. These plants will have been exposed to warm temperatures for germination and early growth and then cooler temperatures when they are transplanted into the garden.
When the weather finally warms, the plants think it is the second growing season and bolt.
Clallam County Master Gardeners suggest planting kale seeds in the garden in May. Soils are warm enough for the seeds to sprout quickly and the risk of subsequent cold temperatures will be minimal. You also can plant kale starts in the garden as early as March, but you may be more likely to see these plants bolt.
The following kale varieties have performed well locally: Beira Tronchuda, Curled Scots, Nero Di Toscana, Improved Dwarf Siberian, Red Russian, Red Ursa and Redbor.
For recommendations for planting times and varieties for other crops, see “Recommended Planting Times and Vegetable Varieties for the North Olympic Peninsula at tinyurl.com/NOPveggies.
Jeanette Stehr-Green is a WSU-certified Clallam County Master Gardener.
‘All About Lavender’
Make sure to join us for the upcoming Green Thumb presentation “All About Lavender” presented by Victor Gonzalez, lavender grower and owner of Victor’s Lavender Farm in Sequim, from noon-1 p.m. Thursday, Sept.22, on Zoom. Gonzalez will provide best practices for lavender planting, spacing and variety selection, and share tips for the right way and best time for trimming. He will also address your lavender questions and provide answers for problems growing lavender in your garden.
Find the link at extension.wsu.edu/clallam/master-gardener-calendar. Or, join by phone at 253-215-8782 (meeting ID 920 0799 1742, passcode 709395).
Presentations cover basic gardening topics relevant to most home gardeners. Seminars are free, but donations to help support the WSU Clallam County Extension Master Gardener program or Master Gardener Foundation of Clallam County are appreciated.